The Z-80 SoftCard is a plug-in Apple II processor card developed by Microsoft to turn the computer into a CP/M system based upon the Zilog Z80 central processing unit (CPU).

This gives Apple II users access to many more business applications, including compilers and interpreters for several high-level languages.

As CP/M requires contiguous freely usable RAM from address zero - which the Apple II doesn't have, since its own 6502 CPU's call stack and zero page and its text mode screen memory cannot be outside the lowest 4 KiB of RAM - addresses are translated in order to move reserved-RAM and non-RAM areas to the top of memory.

SCP built prototypes,[7] Don Burtis of Burtronix redesigned the card, and California Computer Systems manufactured it for Microsoft.

[8] Unsure whether the card would sell, Microsoft first demonstrated it publicly at the West Coast Computer Faire in March 1980.

[1] The SoftCard became the company's largest revenue source in 1980,[10] selling 5,000 units in three months at $349 each, with high sales continued for several years.